Hey guys, need some advise. should I prime a motor that has had the con rod bearings and the oil pump replaced prior to trying to fire it again?
Plugs out, full of oil, crank till pressure.
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Oil pumps, either gear or rotor, are positive displacement pumps, so they are self priming. If they are turning, they pump virtually the same volume per rotation, without regard to any back pressure downstream (short of total blockage). So long as you put a little oil in the new pump, it develops whatever pressure differential it needs to provide flow, down to the vapor pressure of the pumped liquid.
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I process of getting sump ready to be put into place and have a question about the rear gasket for it. I am planning on using the rubber style one vs the cork gasket supplied in the kit. The rubber gasket is a bit too long, so before I trim to fit am I missing something as far as installation. Will it compress more than I think and end up too short after it is installed and compressed?
Rubber will always shrink more than you think so if anything I would only trim off enough to make it a very tight fit, do not allow it to just sit in there āperfectlyā. Always compress rubber and never stretch it.
Well guys, I have a problem. I cannot get the engine to show oil pressure when cranked over, I figure the oil pump needs to be primed. One thing I tried after a bit was to pull the oil filter and hook a hose to the center of the spin on port and pore oil into the motor from a point high above the carbs. I managed to get about a half quart into the motor from that direction, checking the dip stick showed an increase in the oil level, so I figured it was getting through the pumpā¦ Tried it again this morning and still no pressure, even hooked up a mechanical gauge to side of block on oil galley, no pressure. Any ideas out there or should I plan on pulling pan again and pack the pump with grease.
Did you oil the pump? If so, and everything else was prelubed, were it me, Id just fire it up, briefly.
Packing a pump with grease can badly backfire in you: it can send s āplugā of grease into a main or rid journal, or a small cam feed passage, acting as aā¦plug.
Paul,
I didnāt add any oil to the pump, just installed as received. I was hoping by back filling via the oil filter passage to the pump would supply enough oil to prime it. I did use a good layed of new assembly lub on the bearings when I installed them Federal/Mogul stuff. Pulled the distributor hoping I could spin pump via that path, but after looking it over it seems that method is closed based on the design of the distributor/pump drive.
Oops: now you need to pressurize the system.
Okay, I am not sure what you mean, any suggestions?
Just my opinion: Pull the spark plugs, prop the pistons and needle assemblies in the carbs wide open (eliminates fuel flow and cylinder wash down), crank the engine for 30-60 seconds, reinstall spark plugs, pull the piston props and start the engine. You will have oil pressure in seconds.
Oil pumps, whether they are of gear or rotor or gearotor design, are positive displacement. If they are turning they are moving something, whether it is air or liquid, something is being displaced. What you are currently trying to do is displace the trapped air from the pickup tube on the suction side of the oil pump to the pressure side, so that it can generate enough of a pressure differential to lift the oil out of the sump up to the level of the pump. This will happen, but pumps are not efficient air compressors, so it takes longer than your anxiety will tolerate.
Well guys will take it on again tomorrow. Pulled the plug and went to my neighborhood Summit racing warehouse and got an oil system pressure pot. Will let you know how it comes out. Of course, I see Mikeās comments after I get back. Still I will feel better when I can pressurize the system and see that gauge. move.
thanks again,
Thereās nothing wrong with pressurizing the main oil galley downstream of the oil pump, it just will not contribute to bringing the oil pressure up on the pump. That is a supply side issue. Thereās air on the suction side that needs to move to the pressure side before the oil can flow. ( I realize now that my most recent post was almost a word for word duplicate of one from the other day. I blame the shelter in place tequila.)
Thatās is a great line, Mike, you should put it to music. Maybe you can get royalties by selling it to Jimmy Buffett. Or Jerry Jeff Walker.
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I got oil pressure after 18 seconds of crankingā¦plugs outā¦on my fresh rebuild. Oil pump was lubed with oil, not exactly flooded or primed.
I would fill the exit line of the pump and turn the engine backwards so the oil is sucked in the pump in a reverse way.Worked for me several times
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Houston, we have PRESSURE!!!. Did a combination of what Mike and Paul recommended, used my pressure pot a couple of times via the oil galley on the right comer of the block, and pulled the slides and turned the motor over to hopefully clear any air pockets.
After checking the dipstick I feel the engine has a bit too much oil in it, must be close to even with bottom of block. Funny thing when pressure was applied it sat for about 30 seconds then I could hear a rumbling and the pot would empty of contents, I had 80 PSI pushing fluid through, saw a leak where the overflow pipe from the filter goes into sump, guess I might have triggered by pass.
thanks again,
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